Medical System With Multiple Operating Modes for Steering a Medical Instrument Through Linked Body Passages

ABSTRACT

A controller operates in different operating modes to control movement of a distal tip of a medical instrument when inserting and retracting the medical instrument through linked body passages. When inserting the medical instrument, the controller normally operates in an automatic navigation mode unless manually overridden to operate in a manual mode. When retracting the medical instrument, the controller normally operates in a zero-force mode to allow the distal tip to freely move so that it may comply with the shape of the passages as the medical instrument is being retracted through the linked body unless manually overridden to operate in a manual mode.

FIELD OF THE INVENTION

The present invention generally relates to medical systems and inparticular, to a medical system with multiple operating modes forsteering a medical instrument through linked body passages.

BACKGROUND

One type of medical instrument that is steered through body passages isan endoscope. Endoscopes allow physicians to capture images of anddiagnose problems with internal body organs by inserting the deviceeither through a natural orifice or a surgeon created opening andguiding it to a target site within a patient. In some cases, it may alsobe used to perform medical procedures on the internal body organs. Itmay be steerable so that its distal tip is controllably oriented fornavigation purposes. An image capturing device such as a stereoscopic ormonoscopic camera may be provided at its distal tip so that imagescaptured by the camera from that perspective may be viewed on a displayscreen by the surgeon. To perform various medical procedures at thetarget site, surgical tools, such as those used for cutting, grasping,cauterizing, etc., may extend out of the endoscope's distal tip.

Specialized endoscopes may be named for where they are generallyintended to look. Examples include: cystoscopes for looking in thebladder, nephroscopes for looking in the kidney, bronchoscopes forlooking in bronchi of the lung, laryngoscopes for looking in the larynx,otoscopes for looking in the ear, arthroscopes for looking at joints,laparoscopes for looking inside the abdomen, and gastrointestinalendoscopes. In order to look at their intended organs, endoscopes maymove through linked body passages in the body to a target area.

Another type of medical instrument that is steerable through bodypassages is a catheter. Catheters are long slender flexible tubes thatare inserted into a natural bodily cavity or passage for introducing orwithdrawing fluid. Its uses include the drainage of urine from thebladder through the urethra or insertion through a blood vessel into theheart for diagnostic purposes. Catheters may also be inserted in apassage to keep the passage open.

Still other types of medical instruments that are steerable through bodypassages are surgical and diagnostic tools. Examples include such commonmedical implements as forceps for taking tissue samples and electrodesused for cauterization of tissue.

Body passages through which such medical instruments are steered may becircuitous and have varying widths along their lengths. Further, theymay be multi-branched and narrow so that navigation to target areas inthe body is difficult. Also, the passage may comprise sensitive tissuethat is easily harmed by excessive physical contact with the medicalinstrument. As an example of linked body passages, U.S. Pat. No.7,901,348 B2 describes visual-assisted guidance of an ultra-thinflexible endoscope to a predetermined region of interest within thebronchial tree of a lung during a bronchoscopy procedure. As otherexamples of linked body passages, U.S. 2005/0182319 A1 describes imageguided surgery techniques applicable to the blood circulatory system aswell as the air circulatory system of the lung, the digestive system,and the urinary system.

When an operator is inserting a medical instrument through linked bodypassages to a target area in an anatomical structure of a patient, itmay be desirable to assist the operator in navigating the medicalinstrument to the target area. In retracting the medical instrument backout of the linked body passages, care must be taken to avoid harming thepassage walls by excessive physical contact with the medical instrument.Safety for the patient is a primary concern at all times whilecontrolling movement of the medical instrument in the patient.

OBJECTS AND SUMMARY

Accordingly, one object of one or more aspects of the present inventionis a medical system, and method implemented therein, for controlling themovement of a medical instrument through body passages without causingharm to a patient.

Another object of one or more aspects of the present invention is amedical system, and method implemented therein, for providing navigationassistance when useful to an operator for steering a medical instrumentto and/or from a target area through linked body passages in a safe andefficient manner.

Still another object of one or more aspects of the present invention isa medical system, and method implemented therein, for providingautomatic navigation assistance with manual override to a target areathrough linked body passages.

These and additional objects are accomplished by the various aspects ofthe present invention, wherein briefly stated, one aspect is a medicalsystem comprising: a steerable medical instrument; at least oneactuator; and control means for commanding the at least one actuator tocause the medical instrument to be steered according to an insertioncontrol mode after movement of the medical instrument is detected in aninsertion direction and commanding the at least one actuator to allowthe medical instrument to move in compliance with forces exerted againstthe medical instrument after movement of the medical instrument isdetected in a retraction direction.

Another aspect is a method for controlling the steering of a medicalinstrument, the method comprising: detecting movement of the medicalinstrument; and commanding at least one actuator to cause the medicalinstrument to be steered according to an insertion control mode aftermovement of the medical instrument is detected in an insertion directionand commanding the at least one actuator to allow the medical instrumentto move in compliance with forces exerted against the medical instrumentafter movement of the medical instrument is detected in a retractiondirection.

Another aspect is a medical system comprising: an input device; amedical instrument; at least one actuator; and control means forcommanding the at least one actuator to cause the medical instrument tobe steered according to a programmed navigation path in a normal controlmode and for commanding the at least one actuator to cause the medicalinstrument to be steered according to movement of the input devicecommanding such steering when the normal control mode is manuallyoverridden by an operator of the input device.

Yet another aspect is a method for controlling the steering of a medicalinstrument, the method comprising: commanding at least one actuator tosteer the medical instrument according to a programmed navigation pathwhile being moved in an insertion direction; receiving a manual overrideindication; and commanding the at least one actuator to steer themedical instrument according to movement of an input device.

Additional objects, features and advantages of the various aspects ofthe present invention will become apparent from the followingdescription of its embodiments which description should be taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram of a medical instrument which is disposedwithin linked body passages and controlled by a controller of a medicalsystem utilizing aspects of the present invention.

FIG. 2 illustrates a diagram of a distal end of a medical instrumentused in a medical system utilizing aspects of the present invention.

FIG. 3 illustrates a diagram of linked body passages through which amedical instrument may pass through.

FIG. 4 illustrates a block diagram of a medical system utilizing aspectsof the present invention.

FIG. 5 illustrates a flow diagram of a method, utilizing aspects of thepresent invention, for controlling a medical instrument during itsinsertion towards a target area in a patient.

FIG. 6 illustrates a flow diagram of a method, utilizing aspects of thepresent invention, for controlling a medical instrument during itsretraction away from a target area in a patient.

DETAILED DESCRIPTION

FIG. 1 illustrates use of a medical system in which a controller 102commands actuators 103 to move a medical instrument 104 into and out ofand through linked body passages of a patient 150 in response tooperator interaction with an input device 101. The medical instrument104 in this case may be an endoscope, catheter or other medical devicehaving a steerable tip 142 such as shown in FIG. 2. The actuators 103include an actuator 121 for moving the entire medical instrument 104along a rail 124 in an input direction (i.e., insertion into the patient150) and an output direction (i.e., retraction out of the patient 150),as depicted by the two-headed arrow denoted “I/O”. Alternatively, theactuator 121 may be omitted, in which case, an operator may manuallyinsert and retract the medical instrument 104 into and out of the linkedbody passages. The actuators 103 also include actuators 122 and 123 forsteering the steerable tip 142.

FIG. 2 illustrates details of a distal end of the medical instrument 104in which the steerable tip 142 is shown in a non-rotated state in solidline form and in various rotated states in dotted line forms. Themedical instrument 104 includes a flexible body 141 to which thesteerable tip 142 is rotationally coupled. For example, when thesteerable tip 142 is rotated in a pitch direction, it moves as shown inthe illustrated dotted line forms. When the steerable tip 142 is rotatedin a yaw direction, it moves in an orthogonal direction to theillustrated dotted line forms. By rotating the steerable tip 142 in acombination of pitch and yaw, intermediate angles between pitch and yawmay be achieved. In this case, actuator 122 may steer the steerable tip142 in pitch and actuator 123 may steer the steerable tip 142 in yaw.Alternatively, the steerable tip 142 may be rotated in roll about acentral axis of the body 141 and one or both of pitch and yaw usingcorresponding actuators. The flexible body 141 may be passively bendableor actively bendable or a combination thereof. To actively bend theflexible body 141 additional actuators and control elements may beprovided in addition to those already mentioned for steering the medicalinstrument 104.

When the medical instrument 104 is a steerable endoscope, it may haveone or more lumens 145 through which a plurality of fiber optic cables144 and an image capturing device 143 extend. The image capturing device143 may be a stereoscopic or monoscopic camera for capturing images thatare transmitted to and processed by an image processor 108 and displayedon a display screen 109 (shown in FIG. 4). Alternatively, the imagecapture device 143 may be a coherent fiber-optic bundle that couples toan imaging processing system on the proximal end of the instrument 104,such as a fiberscope. One of the fiber optic cables 144 may be coupledat its proximal end to a light source (not shown) for illuminationpurposes at the distal end of the medical instrument 104. Others of thefiber optic cables 144 may be configured with bend or shape sensors suchas Fiber Bragg Gratings (or other strain sensors such as those employingRayleigh scattering) so that light passing through the fiber optic cableis processed by the controller 102 to determine a current position andshape of the medical instrument 104 including the orientation of thesteerable tip 142.

One example of such a steerable endoscope is described in WO 2009/097461A1 entitled “Apparatus and methods for automatically controlling anendoscope,” which is incorporated herein by reference. Details on thedetermination of the endoscope's position and bending using Fiber BraggGratings may be found, for examples, in U.S. 2007/0156019 A1 entitled“Robotic Surgery System Including Position Sensors Using Fiber BraggGratings”, U.S. 2008/0212082 A1 entitled “Fiber Optic Position and/orShape Sensing Based on Rayleigh Scatter”, U.S. 2008/0218770 A1 entitled“Robotic Surgical Instrument and Methods using Bragg Fiber Sensors”, andU.S. 2009/0324161 A1 entitled “Fiber Optic Shape Sensor”, each of whichis incorporated herein by reference.

FIG. 3 illustrates a diagram of linked body passages 152 in a patient150 through which the medical instrument 104 moves under control of thecontroller 102 in response to operator interaction with the input device101. The linked body passages 152 has an entry point 151 through whichthe medical instrument 104 enters, branch passages 154, 155, 156, and157 which provide paths for the medical instrument 104 to reachdifferent target areas in the patient, and walls 153 of tissue. Althoughshown in FIG. 3 as a tree structure with multiple branch passages, thelinked body passages 152 may instead comprise a single lumen or passage.In addition to natural body passages, artificial or surgeon created bodypassages may also be included among the linked body passages 152.

FIG. 4 illustrates, as an example, a block diagram of the medical system100. A controller 102 controls movement of a medical instrument 104 bycommanding actuators 103 according to a current operating mode of thecontroller 102. The controller 102 may be implemented as one or morecentralized or distributed processors executing program code stored inone or more memories, with each of the processors implemented in turn,by one or a combination, of hardware, firmware, and software. Thecurrent operating mode normally depends upon whether the operator iscommanding movement of the medical instrument 104 in an insertiondirection (i.e., into the patient) or a retraction direction (i.e., outof the patient). Default operating modes are provided so that thecurrent operating mode is an automatic navigation mode when movement ofthe medical instrument 104 in the insertion direction is detected andthe current operating mode is a zero-force mode when movement of themedical instrument 104 in the retraction direction is detected, Theprogrammed default modes, however, may be manually overridden forsafety, course alteration, or other purposes. An input device 101 isprovided in the medical system 100 for manual steering of the medicalinstrument 104 when the automatic navigation mode is overridden. Theinput device 101 may also be used for commanding insertion andretraction of the medical instrument 104. Alternatively, such insertionand retraction may be performed by an operator manually moving themedical instrument 104 in the insertion and retraction directions. Alsoincluded in the medical system 100 are the actuators 103, the medicalinstrument 104, a memory 107, a display screen 109, and an imageprocessor 108.

FIG. 5 illustrates, as an example, a flow diagram of a method performedby the controller 102 for controlling the steering of the medicalinstrument 104 during its insertion towards a target area in a patient.In block 501, the method detects movement of the medical instrument 104in the insertion direction by either detecting movement of the inputdevice 101 or movement of the medical instrument 104 using appropriatesensors. In block 502, the method determines whether the movementexceeds a threshold value to avoid false indications of operatorintended insertion movement. Examples of such false indications includenoise in the system or hand tremors when the operator is manuallyinteracting with the input device 101 or manually inserting the medicalinstrument 104. The threshold values may be based upon either a changein position independent of time or a change in position over a specifiedperiod of time (i.e., a velocity).

If the determination in block 502 is NO, then the method loops back toblock 501. On the other hand, if the determination in block 502 is YES,then the method proceeds to block 503 where it determines the currentpose (i.e., position and orientation) of the distal tip 142 of themedical instrument 104. In block 504, the method next determines thesteering direction according to a programmed navigation path using thecurrent pose of the medical instrument 104. The navigation path may bedetermined pre-operatively or inter-operatively using images of thepatient anatomy such as those generated using Computed Tomography (CT)scans, Magnetic Resonance imaging (MRI) scans, and the like.

In normal operation, the method then proceeds to block 506 where itoperates in an automatic navigation mode to command actuators 122 and123 to steer the medical instrument 104 along the programmed navigationpath according to the determined steering direction. After performingblock 506, the method then proceeds by jumping back to block 501 toperform another process cycle.

The method is also provided with a manual override feature which islogically shown as block 505 (interposed between blocks 504 and 506) inwhich a determination is made whether the operator has activated amanual override. The operator may do this by activating a manualoverride switch located, for example, on the input device 101, or bysimply moving the input device 101 so as to “overpower” the navigationmode and command the steering actuators 122 and 123 to steer thesteerable tip 142 as desired. Overpower in this sense means that theoperator has commanded through the input device 101 sufficient movement(e.g., exceeding a threshold amount) of the steerable tip 142 in asteering direction that is in contradiction to that of the navigationmode command. Although shown as a determination in block 505, the manualoverride may be implemented as a conventional “system interrupt” whichcauses the controller 102 implementing the method to jump to block 507so as to allow manual mode operation in which the operator may take overcontrol of steering the medical instrument 104. In particular, in manualmode operation, the controller 102 allows the operator full control ofsteering the steerable tip 142 of the medical instrument 104 bycommanding the tip steering actuators 122 and 123 to steer the steerabletip 142 in response to operator interaction with the input device 101that commands such steering action.

While operating in manual mode, block 508 may optionally be performed inwhich the method causes a graphical indication of the steering directiondetermined in block 504 to be shown in the display screen 109.Alternatively, or additionally, the method may cause a nudging force tobe provided on the input device 101 so as to encourage the operator tosteer the medical instrument 104 in the steering direction determined inblock 504. When the operator desires to transfer control back toautomatic navigation mode, the override may be released and the methodjumps back to block 501. Subsequently, after performing a manualoverride, an updated navigation path may be determined using the currentpose of the medical instrument as determined in block 503 and a newsteering direction determined using the updated navigation path in block504, since the medical instrument 104 may no longer be on the originalnavigation path following the manual override. In this way, each timethe operator switches from manual to navigation mode, a new navigationpath from the current instrument position to the target area may bedetermined in a manner similar to a car navigator which automaticallyre-computes the path to a destination when the driver drives off thenavigation path. The navigation path (original and updated) may bestored in the memory 107 so that it is accessible to the controller 102.

FIG. 6 illustrates, as an example, a flow diagram of a method performedby the controller 102 for controlling a medical instrument 104 duringits retraction away from a target area in a patient. In block 601, themethod detects movement of the medical instrument 104 in the retractiondirection by either detecting movement of the input device 101 ormovement of the medical instrument 104 using appropriate sensors. Inblock 602, the method determines whether the movement exceeds athreshold value to avoid false indications of operator intendedretraction movement (such as previously described in reference to block502 of FIG. 5). If the determination in block 602 is NO, then the methodloops back to block 601.

In normal operation, the method then proceeds to block 604 where itoperates in a zero-force mode to command actuators 122 and 123 to allowthe medical instrument 104 to move in compliance with forces exertedagainst the medical instrument 104 (such as exerted by the passage wallsas the medical instrument travels through a passage). For example, thecontroller 102 may actively control the steerable tip 142 so as tominimize contact forces with the walls 153 of the linked body passages152 based upon detected interaction forces. As another example, thecontroller 102 may deactivate the steering actuators 122 and 123 so thesteerable tip 142 is free to move in compliance with the walls 153 ofthe linked body passages 152. Thus, the passage walls which may be ofsensitive tissue are subjected to only minimal harm during theretraction of the medical instrument 104. The method then proceeds byjumping back to block 601 to perform another process cycle.

The method is also optionally provided with a manual override featurewhich is logically shown as blocks 603 and 605. The manual override inthis case would operate similarly to the manual override of blocks 505and 507 as described in reference to FIG. 5. After completing the manualoverride, the method then jumps back to block 601 to re-enter normalmode retraction operation.

Regardless of which operating mode the controller 102 is operating in,it is noteworthy that the operator always has control over the directionand speed of the movement of the medical instrument 104. In particular,even when the controller 102 is automatically steering the steerable tip142, the operator may stop all action by ceasing to command insertion ofthe medical instrument 104. The operator may also slow down such actionby slowing down the commanded rate of the insertion.

Although the various aspects of the present invention have beendescribed with respect to one or more embodiments, it will be understoodthat the invention is entitled to full protection within the full scopeof the appended claims and is not to be limited by the describedembodiments.

What is claimed is:
 1. A medical system comprising: a steerable medicalinstrument; at least one actuator; and control means for commanding theat least one actuator to cause the medical instrument to be steeredaccording to an insertion control mode after movement of the medicalinstrument is detected in an insertion direction and commanding the atleast one actuator to allow the medical instrument to move in compliancewith forces exerted against the medical instrument after movement of themedical instrument is detected in a retraction direction.
 2. The medicalsystem of claim 1, wherein the insertion control mode commands the atleast one actuator to steer the medical instrument according to aprogrammed navigation path.
 3. The medical system of claim 2, whereinthe programmed navigation path indicates a steering direction determinedfrom a current insertion position of the medical instrument.
 4. Themedical system of claim 2, wherein the insertion control mode commandsthe at least one actuator to steer the medical instrument according tooperator interaction with a control device if the operator overrides theprogrammed navigation path.
 5. The medical system of claim 4, whereinthe control means causes a nudging force to be exerted on the controldevice so as to indicate a steering direction in conformance with theprogrammed navigation path.
 6. The medical system of claim 4, furthercomprising a display screen, wherein the control means causes anindication of a steering direction in conformance with the programmednavigation path to be displayed on the display screen.
 7. The medicalsystem of claim 4, wherein the control means updates the programmednavigation path according to a current pose of the medical instrumentafter the operator releases the overriding of the programmed navigationpath.
 8. The medical system of claim 1, wherein the control meansdetects movement of the medical instrument in the insertion direction bya change exceeding a threshold amount in the insertion direction.
 9. Themedical system of claim 1, wherein the control means detects movement ofthe medical instrument in the retraction direction by a change exceedinga threshold amount in the retraction direction.
 10. The medical systemof claim 1, wherein the insertion control mode commands the at least oneactuator to steer the medical instrument according to operatorinteraction with a control device.
 11. The medical system of claim 10,wherein the control means causes a nudging force to be exerted on thecontrol device so as to indicate a steering direction in conformancewith a programmed navigation path.
 12. The medical system of claim 10,further comprising a display screen, wherein the control means causes anindication of a steering direction in conformance with a programmednavigation path to be displayed on the display screen.
 13. The medicalsystem of claim 1, wherein the steerable medical instrument is moved inthe insertion and retraction directions by an operator manually pushingand pulling the steerable medical instrument into and out a passage. 14.A method for controlling the steering of a medical instrument, themethod comprising: detecting movement of the medical instrument; andcommanding at least one actuator to cause the medical instrument to besteered according to an insertion control mode after movement of themedical instrument, is detected in an insertion direction and commandingthe at least one actuator to allow the medical instrument to move incompliance with forces exerted against the medical instrument aftermovement of the medical instrument is detected in a retractiondirection.
 15. A medical system comprising: an input device; a medicalinstrument; at least one actuator; and control means for commanding theat least one actuator to cause the medical instrument to be steeredaccording to a programmed navigation path in a normal control mode andfor commanding the at least one actuator to cause the medical instrumentto be steered according to movement of the input device commanding suchsteering when the normal control mode is manually overridden by anoperator of the input device.
 16. The medical system of claim 15,wherein the control means commands the at least one actuator to causethe medical instrument to move in an insertion direction in response tomovement of the input device commanding such insertion while causing themedical instrument to be steered according to the programmed navigationpath in the normal control mode.
 17. The medical system of claim 16,wherein the programmed navigation path indicates a steering directiondetermined from a current insertion position of the medical instrument.18. The medical system of claim 16, wherein the insertion control modecommands the at least one actuator to steer the medical instrumentaccording to operator interaction with a control device if the operatoroverrides the programmed navigation path.
 19. The medical system ofclaim 18, wherein the control means causes a nudging force to be exertedon the control device so as to indicate a steering direction inconformance with the programmed navigation path.
 20. The medical systemof claim 18, further comprising a display screen, wherein the controlmeans causes an indication of a steering direction in conformance withthe programmed navigation path to be displayed on the display screen.21. The medical system of claim 18, wherein the control means updatesthe programmed navigation path according to a current pose of themedical instrument after the operator releases the overriding of theprogrammed navigation path.
 22. The medical system of claim 15, whereinthe control means detects movement of the medical instrument in theinsertion direction by a change exceeding a threshold amount in theinsertion direction.
 23. The medical system of claim 15, wherein themedical instrument is moved in insertion and retraction directions by anoperator manually pushing and pulling the medical instrument into andout of a passage.
 24. A method for controlling the steering of a medicalinstrument, the method comprising: commanding at least one actuator tosteer the medical instrument according to a programmed navigation pathwhile being moved in an insertion direction; receiving a manual overrideindication; and commanding the at least one actuator to steer themedical instrument according to movement of an input device.